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Samenvatting FCH-30306 Food Ingredient Functionality (FCH30306)
This summary covers the reader (Food Ingredient Functionality), the tutorials and knowledge clips given during this course.
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Summary reader and tutorials/knowledge clips FIFFCH-30306 Food Ingredient Functionality 2020-2021
Food Polysaccharides
Pectin:
• 1. Acid-extracted from agricultural by-products (apple pomace and citrus peel- are
part of the cell wall of almost all dicotylic plants. In the cell wall (mainly in the
middle lamella and primary cell wall next to cellulose and hemicellulose, pectin is
bound to other cell wall polysaccharides for example hemicelluloses). Apple and
citrus pomace must be dried in order to prevent degradation by pectolytic enzymes.
• 2. Most pectin is manufactured by extraction with hot aqueous acid solution at high
temperature 50-90 degrees (differences from alginate) for 3-12 hours (long time)
at pH 1-3. The extract is then filtered, precipitated with ethanol, drum- or spray dried,
grinded and standardized to a certain gel strength by blending with a filler.
• Methyl esterified pectin: happens at a low pH and temperatures below 50 degrees.
• Amidated pectin: Methyl esters are converted in amide groups, while also part of the
methyl esters will be removed by the high pH. Amidated pectin may typically have
30% of their galacturonic acids being methyl esterified while up to 20% of the
galacturonic acids are amidated.
• The most important is the homo(poly)galacturonan region (HG), consisting of main
chain consisting a-(1,4) linked linear D-galacturonic acid, which are strongly linked to
each other and heat stable. The D-galacturonic acid units have an acid group within
their structure. These acids groups can be methylesterified (at the carboxyl groups at
C-6)
• Other pectin regions: RG-I (rhamnosyl and galacturonosyluronic acid residues) and
RG-II (highly branched polysaccharide and consists of galacturonosyl residues)
However, only a gel can be formed in the HG region.
• Gel formation: Calcium gel (Two pectin strands can be connected and form ionic
bonds through a series of neighbouring calcium bridged within the so-called ‘egg-
box’ model. Sugar-acid gel (the added sugar is hydroscopic which brings the pectin
chains closer, being then able to interact. By additionally lowering the pH with the
acid, the low number of remaining carboxyl groups become neutral and a three-
dimensional network of pectin molecules is formed). In summary, 4 pectin molecules
around 1 calcium molecule (2 acids and 2 hydroxyl groups for further stabilization)
• Amidated LM-pectin gel (gels at lower pectin concentration and less calcium than for
LM-pectin is required)= spreadable and similar to LM-pectin gel (above pH=3.5)
Semi-firm and similar to HM-pectin gels (below pH=3.5)
May be used in dairy products rather than LM-pectin in cases LM-pectin leads to a
too quickly formed or to a too strong gel.
• Most stable at pH 3-4. Can be degraded at ambient T and neutral or high pH and at
the same conditions, the galacturonic backbone is degraded into molecule of lower
mass by the so-called B-elimination showing a reduced gelling power. This will
happen much more in HM pectin compared to LM pectins.
1
,Alginate:
• Extracted from various brown seaweed. Mainly from Macrocystis, Laminaria,
Lessonia species. Is extracted using hot alkaline solution. After removal of the
insoluble material, a solution of sodium alginate is obtained. The alginate is
precipitated from the solution either by adding calcium chloride or acid. The product
is alginic acid, which is then converted back to sodium alginate and dried, resulting
in sodium alginate powder that is commonly used in food products.
• Consists of. 2 building units: Mannuronic acid and guluronic acid linked with (1,4
linkages). The ratio between M and G in a certain alginate depends on the seaweed.
• The properties of alginate are influenced by its G:M ratio, block distribution, and
environmental factors like pH and the presence of ions.
• Insoluble. Insolubility is used to isolate alginate during the extraction process.
Sodium-, potassium-, or ammonium- alginate is soluble in water. When alginate is
solubilized, the solution is viscous. Sodium alginate cannot be used to thicken acidic
products, because it is unstable in acidic conditions.
• Stable at high T and pH since, in contrast to pectin, no ester groups are present
limiting B-elimination.
• Two types of gels formed: 1. Alginic acid gel: By slow acidification of sodium
alginate solution. Is known to have syneresis upon storage. 2. Calcium gel: Can be
formed without heating and is stable against heating. Calcium can interact strongly
only with G-blocks and not with M-blocks or MG-blocks. But if a weak gel is
required, than, M-rich alginate might be a better option.
Carrageenan:
• Extracted from various seaweed classified as red algea. Extracted from the seaweed in
hot alkali. After centrifugation or filtration to obtain a clear solution of
carrageenan, the carrageenan is precipitated by alcohol, followed by drying.
• Is a linear polysaccharide, with a backbone that consists of disaccharide building
blocks built of galactose and anhydrogalactose linkages (=labile). Those residues can
be sulfated, depending on the type of carrageenan.
• There are three main types: Kappa (one sulfate group located on the O-4 of the
galactosyl residue), iota (one sulfate group located on the O-4 of the galactosyl
residue + on the O-2 of the anhydrogalactosyl residue), and lambda (3 sulfate groups
on the galactosyl residues).
2
,• Besides, you have mu- and nu-carrageenan which are precursors of kappa and iota
carrageenan. Instead of anhydrogalactosyl residue they have galactosyl residue
carrying a sulfate group at O-6. During alkaline extraction, the sulfate group may
fall off while anhydrogalactosyl residue is formed.
• Kappa- and iota-carrageenan segments could be present in one single carrageenan
molecule.
• When it’s soluble, the viscosity of carrageenan increases with increasing
concentration.
• For kappa and iota, small conc of salt can increase the viscosity. For lambda, salts can
decrease the viscosity because salts can neutralize some of the sulfate groups.
• Will be partly hydrolysed (and thus degraded) at low pH due to the
anhydrogalactose residue. This means, less suitable for an acidic product.
• The anhydrogalactosyl residue is necessary to the gelling property.
• The gel formed by kappa-carrageenan with potassium (cold T) is firm and brittle,
syneresis and is not stable against freeze-thaw cycle (so cannot be used in ice
creams).
• The gel formed by iota-carrageenan with calcium (cold T) is elastic, cohesive, stable
against syneresis and freeze-thaw cycle.
• Interaction of carrageenan with proteins and other polysaccharides: Efficient
ingredient for stabilizing and gelling milk products because it forms complexes with
milk proteins (1. Direct interaction negatively charged carrageenan with positively
charged amino acids. 2. Indirect interaction with negatively charged carrageenan,
negatively charged amino acids and calcium) combined with its own gelling
properties (part of the carrageenan will also interact amongst each other through
helices).
• Kappa carrageenan shows a synergism with locust bean gum (LBG) in aqueous gel
systems (Kappa carrageenan is able to associate with galactose-free mannan regions
of LBG, much lower levels of hydrocolloid is needed compared to individual
systems.). The interaction will increase the gel strength, water binding capacity, gel
structure from brittle to elastic and decreases syneresis
3
, Galactomannan:
• Are storage polysaccharides present in the endosperm of seeds of the guar plant, carob
tree, tara tree, fenugreek plant and cassia tree.
• Does not form a gel by itself
• Highly branched
• Obtained by dehulling and milling the seeds of the trees/plants. If more pure
galactomannan is required, purification from the seed powder by washing with
ethanol or isopropanol.
• The ratio of galactose and mannose determines the solubility and increases when G:M
is higher. Galactomannan is soluble in cold water resulting is a high viscous solution.
When M:G is higher, such structure are rigid and easy to aggregate and become
insoluble. So, the higher the number of substituted galactosyl residues, the better the
solubility.
• High viscosity possible. Nevertheless, the viscosity will drop with decreasing MW
when the galactomannans would be heated at rather low pH values.
• Interaction with xanthan:
The non-substituted part of galactomannan (so the part with no galactose substituents)
can interact via cations or with a junction zone with the helical xanthan structure.
Galactomannan and xanthan gum are not a gelling agent when used alone, but
together they are able to form a gel (called ‘interaction gel’)
• In conclusion, the degree of substitution determines the solubility, viscosity, and
interaction with other polysaccharides.
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